1. Field of the Invention
The present invention relates to a multipolar electrical connector, and more particularly to a multipolar electrical connector that, as a counter connector, uses a single-head plug having a pole shaft in which center poles are disposed in plural positions in the axial direction, respectively (hereinafter, such a multipolar electrical connector is referred to merely as "multipolar connector"). The invention relates also to a multipolar connector wherein a boss portion protrudes from the body to which a predetermined contact piece is attached, and contact pieces of two or more poles can be added by using the boss portion. A multipolar connector of this kind can be preferably used in the field of a mobile communication apparatus such as a portable telephone, and that of an electric or electronic apparatus to which a portable cassette tape recorder, a radio receiver, and the like belong.
2. Description of the Prior Art
A single-head plug includes poles (the above-mentioned center poles) which are disposed in plural positions in the axial direction of a single pole shaft, respectively. A multipolar connector is structured so that the body has a space (insertion space) into which a pole shaft of such a single-head plug is to be inserted. A plurality of contact pieces are incorporated into the insertion space. Generally, such a multipolar connector is well known as a jack type multipolar connector. A multipolar connector of this kind has been developed so as to be used in a portable telephone, a portable cassette tape recorder, a portable radio receiver, and the like. In order to correspond to the recent tendency to miniaturization of an apparatus, such a multipolar connector is requested to be microminiaturized. Furthermore, in order to cope with increased functions of an apparatus, a multipolar connector is requested to have a larger number of poles.